The present invention is directed to a method for speaker recognition in a telephone switching system, wherein speech specimens are input into telephone terminal equipment connected to the telephone switching system and are supplied to the switching system within the framework of a speaker recognition test. The speech specimens are sampled with a prescribed, first frequency, and the samples formed are supplied to a means arranged in the switching system that, by comparing reference speech specimens originally deposited in the switching system and speech specimens input within the framework of the speaker recognition test, forms a first signal that identifies a recognition of the speaker or forms a second signal that indicates that recognition of the speaker has not occurred.
AT & T Technical Journal, September/October 1986, Volume 65, Issue 5, pp. 68-74 discloses a system referred to as "A Voice Password System for Access Security" and discloses a method for speaker verification. The system is connected to a telephone network and is composed of what is referred to as a speech verification unit, a computer and an operations-oriented means. Within the framework of a verification test, speakers to be verified must input an identification number into telephone terminal equipment connected to the system and must speak a sentence composed of a plurality of passwords (password phrase). The speech specimens are transmitted via the telephone network and are supplied to the speech verification unit. Auto-correlation coefficients are first calculated for the signals arriving there. Following thereupon, these auto-correlation coefficients are converted into LPC (linear predictive coding) coefficients. These are in turn modified according to the Cepstrum technique. The modified coefficients are finally subjected to a further procedure (channel normalization). Although the implementation of the various procedures leads to lower error rates, it also requires a considerable outlay for eliminating disturbing influences that derive due to the transmission of the speech specimens over the telephone network.